EwE 2018-2020 2J3K (North part) - vulnerability sensitivity analysis
Vajas Pablo
2025-05-01
1 Does the cod’s vulnerability allow it to increase its abundance sufficiently at F=0?
2 First approach: run all simulations fitted at V=2, then re-run them with harp seal V=4 unfitted LoD
2.1 Cod and Capelin biomass versus Harp seal vulnerability change
2.1.1 Note
The present simulations are analogous to those of Vajas et al., but with three values of v (vulnerability) for ‘harp seal’ (applied to the harp seal column for all predated species). The figures and tables present a comparison of the proportion of change between the default baseline of v=2 and the other v values (implying a more top-down effect from harp seal on the ecosystem).
2.1.2 Cod simulation : F scenario V=2 versus V=4
2.1.3 Cod simulation : F scenario V=2 versus V=10
2.1.4 Caplin simulation : F scenario V=2 versus V=4
2.1.5 Caplin simulation : F scenario V=2 versus V=10
2.1.6 Harp seal simulation : F scenario V=2 versus V=4
2.1.7 Harp seal simulation : F scenario V=2 versus V=10
2.1.8 Harp seal trends between V=2, V=4, V=10
3 Group. Impacted
3.1 F Cod simulation : harp seal vulnerability change
3.1.1 Blank
3.1.2 Default results V=2
3.1.3 Results with V=4
3.1.4 Results with V=10
3.1.5 Changes between V2 and V4
3.1.6 Changes between V2 and V10
3.2 F capelin simulation : harp seal vulnerability change
3.2.1 Blank
3.2.2 Default results V=2
3.2.3 Results with V=4
3.2.4 Results with V=10
3.2.5 Changes between V2 and V4
3.2.6 Changes between V2 and V10
3.3 F Harp seal simulation : harp seal vulnerability change
3.3.1 Blank
3.3.2 Default results V=2
3.3.3 Results with V=4
3.3.4 Results with V=10
3.3.5 Changes between V2 and V4
3.3.6 Changes between V2 and V10
4 Second approach: run all simulations fitted at V=2, then re-run them with harp seal V=4 fitted new LoD scale.
In the first approach, we applied changes in V to the exact simulations proposed in Vajas et al. However, although we ran the simulations with the same values of F, the correspondence between [F and LoD for v=2] and [F and LoD for V=4 or 10] is not the same. Here, for the column of harp seals at V=4 and V=10, we respectively recalculate the exact LoD values 0%, 10%, 20%, etc. So here we compare a true LoD 10% (v=2) with another true LoD 10% (V=4 and V=10).
4.1 New LoD approximation
4.1.1 Blank
4.1.2 Cod LoD check, harp seal v = 4
4.1.3 Cod, harp seal v = 10
4.1.4 Capelin, harp seal v = 4
4.1.5 Capelin, harp seal v = 10
4.1.6 Harp seal, harp seal v = 4
4.1.7 Harp seal, harp seal v = 10
4.2 New LoD simulalations
4.2.1 Note
Here, after finding all the F value for LoD value matches, we run the final simulations.
4.2.2 Cod reference table
4.2.3 Cod, harp seal V=4
4.2.4 Cod, harp seal V=10
4.2.5 Cod, Changes between V2 and V4
4.2.6 Cod, Changes between V2 and V10
4.2.7 Capelin reference table
4.2.8 Capelin, harp seal V=4
4.2.9 Capelin, harp seal V=10
4.2.10 Capelin, Changes between V2 and V4
4.2.11 Capelin, Changes between V2 and V10
4.2.12 Harp seal reference table
4.2.13 Harp seal, Harp seal V=4
4.2.14 harp seal, Harp seal V=10
4.2.15 Harp seal, Changes between V2 and V4
4.2.16 Harp seal, Changes between V2 and V10
5 Summary & comparison vulnerability sensitivity approach
5.1 First approach
5.1.1 Blank
5.1.2 Cod
5.1.3 Capelin
5.1.4 Harp seal
5.2 Second approach
5.2.1 Blank
5.2.2 Cod
5.2.3 Capelin
5.2.4 Harp seal
5.3 Species changes
5.3.1 Blank
5.3.2 Capelin
## Group_number Group_name
## 1 12 Atlantic cod greater than 35cm5.3.3 Harp seal
## Group_number Group_name
## 1 11 Greenland shark
## 2 14 Greenland halibut
## 3 22 Other large benthivorous fish6 Level of Recovery - harp seal vulnerability sensitivity
For the new LoR, the approach is slightly different. As the LoR levels are estimated from a fixed reference value, this will not change with changes in vulnerability. So for these LoR levels, as in the first approach, we have simply run the Vajas et al. simulations with different levels of harp seal vulnerability (harp seal column as predator). The aim is to check the sensitivity of biomass forcing to changes in vulnerability.
6.1 Vulnerability Sensitivity Analysis
6.1.1 Blank
6.1.2 Cod simulation : B scenario V=2 versus V=4
6.1.3 Cod simulation : B scenario V=2 versus V=10
6.1.4 Caplin simulation : B scenario V=2 versus V=4
6.1.5 Caplin simulation : B scenario V=2 versus V=10
6.2 B Cod simulation : harp seal vulnerability change
6.2.1 Blank
6.2.2 Default results V=2
6.2.3 Results with V=4
6.2.4 Results with V=10
6.2.5 Changes between V2 and V4
6.2.6 Changes between V2 and V10
6.3 B capelin simulation : harp seal vulnerability change
6.3.1 Blank
6.3.2 Default results V=2
6.3.3 Results with V=4
6.3.4 Results with V=10
6.3.5 Changes between V2 and V4
6.3.6 Changes between V2 and V10
6.4 Species change
6.4.1 Blank
6.4.2 Capelin
## Group_number Group_name
## 1 19 American plaice greater than 35cm
## 2 20 American plaice less than 35cm
## 3 27 Sandlance